Dashblock - Turn any website into an API
Slack Events API - Subscribe to events in Slack via HTTP
Sheety - Turn any Google sheet into an API instantly, for free. Power websites, apps, or whatever you like, all from a spreadsheet. Changes to your spreadsheet update your API in realtime. Neat
Postman - The Collaboration Platform for API Development
Architect 7.0 (Chupacabra) - Blazing fast, modern, lock-in-free web apps without ever having to manage a single server.
Sheetson - Instantly turn any Google Sheet into RESTful API